JP7135134B2 - Injection device - Google Patents

Description

The present invention relates to an injection device.

The electric injection molding machine described in Patent Document 1 has an injection device that fills a resin into a cavity space of a mold device. The injection device includes a heating cylinder that heats and melts resin, a screw that is rotatably and reciprocally arranged in the heating cylinder, a metering motor that rotates the screw, and an injection motor that moves the screw forward and backward. Prepare. Since the screw, metering motor, and injection motor are arranged on the same axis, inertia is small and responsiveness is good.

WO2005/037519

Conventionally, a spline shaft is provided which is splined to the tubular rotor of the metering motor and transmits the driving force of the metering motor and the driving force of the injection motor to the screw. A coupling connects the spline shaft and the screw, and the coupling is disposed inside the rotor of the metering motor.

In the past, the rotor of the metering motor and the coupling were prone to galling, and the frequency of maintenance was high.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its main object is to provide an injection apparatus that suppresses galling between the rotor and the coupling of the metering motor.

In order to solve the above problems, according to one aspect of the present invention,
a screw that is rotatably and reciprocally arranged inside a cylinder that heats the molding material ;
a coupling connected to the screw and spline-connected to the inner side of a cylindrical rotor of the metering motor so as to transmit the driving force of the metering motor for rotating the screw and the driving force of the injection motor for advancing and retreating the screw;
an annular packing held by one of the rotor and the coupling and slidably contacting the other;
a slide ring held by one of the rotor and the coupling and slidably contacting the other ;
An injection device is provided , wherein the hardness of the slide ring is harder than the hardness of the annular packing .

According to one aspect of the present invention, there is provided an injection device that suppresses galling between the rotor of the metering motor and the coupling.

It is a figure which shows the state at the time of the completion of filling of the injection molding machine by one Embodiment. It is a figure which shows the state at the time of the completion of weighing of the injection molding machine by one Embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In each drawing, the same or corresponding configurations are denoted by the same or corresponding reference numerals, and descriptions thereof are omitted.

FIG. 1 is a diagram showing a state of an injection molding machine according to one embodiment when filling is completed. FIG. 2 is a diagram showing a state of the injection molding machine according to one embodiment when weighing is completed.

The injection molding machine has a frame Fr, an injection device 40 and a control device 90 . Hereinafter, the moving direction of the screw 43 during filling (left direction in FIGS. 1 and 2) is defined as forward, and the moving direction of screw 43 during weighing (right direction in FIGS. 1 and 2) is defined as rearward.

The injection device 40 is installed on a slide base Sb that can move back and forth with respect to the frame Fr, and can move back and forth with respect to the mold device. The injection device 40 is brought into contact with the mold device and fills the cavity space in the mold device with the molding material. A molded product is obtained by cooling and solidifying the molding material filled in the cavity space. The injection device 40 has, for example, a cylinder 41, a nozzle 42, a screw 43, a cooler 44, a metering motor 45, an injection motor 46, a pressure detector 47, a heater 48, a temperature detector 49 and the like.

The cylinder 41 heats the molding material supplied inside from the supply port 41a. A supply port 41 a is formed in the rear portion of the cylinder 41 . A cooler 44 such as a water-cooled cylinder is provided on the outer periphery of the rear portion of the cylinder 41 . A heater 48 such as a band heater and a temperature detector 49 are provided on the outer periphery of the cylinder 41 ahead of the cooler 44 .

The cylinder 41 is divided into a plurality of zones in the axial direction of the cylinder 41 (horizontal direction in FIGS. 1 and 2). A heater 48 and a temperature detector 49 are provided for each zone. For each zone, the controller 90 controls the heater 48 so that the temperature detected by the temperature detector 49 becomes the set temperature.

A nozzle 42 is provided at the front end of the cylinder 41 and pressed against the mold device. A heater 48 and a temperature detector 49 are provided around the nozzle 42 . The controller 90 controls the heater 48 so that the detected temperature of the nozzle 42 becomes the set temperature.

The screw 43 is arranged in the cylinder 41 so as to be rotatable and advanceable. When the screw 43 is rotated, the molding material is sent forward along the helical groove of the screw 43 . The molding material is gradually melted by the heat from the cylinder 41 while being sent forward. The screw 43 is retracted as the liquid molding material is fed forward of the screw 43 and accumulated at the front of the cylinder 41 . After that, when the screw 43 is advanced, the molding material in front of the screw 43 is injected from the nozzle 42 and filled in the mold device. The screw 43, metering motor 45, and injection motor 46 are arranged on the same straight line.

A metering motor 45 rotates the screw 43 . Rotational motion of the metering motor 45 is transmitted to the coupling 51 spline-connected to the rotor 45 a of the metering motor 45 and transmitted from the coupling 51 to the screw 43 .

The coupling 51 has, for example, as shown in FIGS. 1 and 2, a screw attachment portion 52 to which the screw 43 is attached, and a metering spline shaft 53 spline-coupled to the rotor 45a. 1 and 2, the metering spline shaft 53 is formed separately from the screw mounting portion 52 and connected to the screw mounting portion 52, but may be formed integrally with the screw mounting portion 52. FIG.

The metering spline shaft 53 is disposed inside the tubular rotor 45a of the metering motor 45 and is spline-coupled to the rotor 45a. The metering spline shaft 53 has a plurality of keys 53a on its outer periphery at intervals in the circumferential direction. The rotor 45a of the metering motor 45 has a plurality of key grooves in its inner periphery into which a plurality of keys 53a are slidably inserted. The number of keys 53a and the number of key grooves may be one. The key 53a of the metering spline shaft 53 may be arranged at the rear (more preferably the rear end) of the coupling 51 as shown in FIGS. trailing edge).

The metering motor 45 is fixed to the injection frame 54 that advances and retreats together with the slide base Sb. The injection frame 54 has a front support 54a, a rear support 54b, and a connecting rod 54c connecting the front support 54a and the rear support 54b. The rear end of the cylinder 41 and the stator 45b of the metering motor 45 are fixed to the front support 54a. A stator 46b of the injection motor 46 is fixed to the rear support 54b.

The injection motor 46 is fixed to the injection frame 54 and advances and retreats the screw 43 . The rotary motion of the injection motor 46 is converted into rotary linear motion of a drive shaft 55 that is spline-coupled to the rotor 46a of the injection motor 46 and screwed into a screw nut 58, which will be described later, so that the drive shaft 55 is rotatably supported. is converted into a linear motion of the coupling 51 holding the bearing 56 to move. As the coupling 51 advances and retreats, the screw 43 advances and retreats.

The drive shaft 55 is rotatably supported by an injection spline shaft 55a spline-connected to the rotor 46a of the injection motor 46, a screw shaft 55b screwed into a screw nut 58 fixed to the rear support 54b, and bearings 56. and a rotating shaft 55c. The injection spline shaft 55a, the screw shaft 55b, and the rotary shaft 55c are arranged on the same straight line in this order from the rear side to the front side. Between the screw shaft 55b and the screw nut 58, balls or rollers may be interposed.

The coupling 51 linearly moves due to the rotary linear motion of the drive shaft 55 . Since the coupling 51 and the metering motor 45 are spline-connected, the metering motor 45 does not advance or retreat when the coupling 51 advances or retreats. Since the injection motor 46 does not include the metering motor 45 in the driving target, the inertia of the driving target of the injection motor 46 is small, and the acceleration of the screw 43 at the start of forward movement is fast.

The pressure detector 47 is provided in the force transmission path between the injection motor 46 and the screw 43 and detects the load acting on the pressure detector 47 . For example, pressure detector 47 is attached to rear support 54b and screw nut 58 to detect the load acting on pressure detector 47. As shown in FIG. Incidentally, the position of the pressure detector 47 is not particularly limited.

Pressure detector 47 sends a signal indicating the detection result to controller 90 . The detection result of the pressure detector 47 is used for controlling and monitoring the pressure that the screw 43 receives from the molding material, the back pressure against the screw 43, the pressure that the screw 43 acts on the molding material, and the like.

The control device 90 has a CPU (Central Processing Unit) 91, a storage medium 92 such as a memory, an input interface 93, and an output interface 94, as shown in FIGS. The control device 90 performs various controls by causing the CPU 91 to execute programs stored in the storage medium 92 . The control device 90 also receives signals from the outside through an input interface 93 and transmits signals to the outside through an output interface 94 . The control device 90 controls the filling process, the holding pressure process, the weighing process, and the like.

In the filling process, the injection motor 46 is driven to advance the screw 43 at a set speed, and the liquid molding material accumulated in front of the screw 43 is filled into the cavity space in the mold device. The position and speed of the screw 43 are detected using the encoder 46c of the injection motor 46, for example. The encoder 46c detects rotation of the injection motor 46 and sends a signal indicating the detection result to the control device 90. FIG. When the position of the screw 43 reaches the set position, switching from the filling process to the holding pressure process (so-called V/P switching) is performed. The set speed of the screw 43 may be changed according to the position of the screw 43, time, and the like.

After the position of the screw 43 reaches the set position in the filling process, the screw 43 may be temporarily stopped at the set position, and then the V/P switching may be performed. Immediately before the V/P switching, instead of stopping the screw 43, the screw 43 may be moved forward or backward at a slow speed.

In the holding pressure process, the injection motor 46 is driven to push the screw 43 forward with a set pressure to apply pressure to the molding material in the mold device. The shortage of molding material due to cooling shrinkage can be replenished. The pressure of the molding material is detected using a pressure detector 47, for example. Pressure detector 47 sends a signal indicating the detection result to controller 90 .

In the holding pressure process, the molding material in the cavity space inside the mold device is gradually cooled, and when the holding pressure process is completed, the entrance of the cavity space is closed with the solidified molding material. This state is called a gate seal, and prevents the molding material from flowing back from the cavity space. After the holding pressure process, the cooling process is started. In the cooling step, solidification of the molding material in the cavity space is performed. A weighing step may be performed during the cooling step to shorten the molding cycle.

In the weighing process, the weighing motor 45 is driven to rotate the screw 43 at a set number of revolutions, and the molding material is fed forward along the helical groove of the screw 43 . Along with this, the molding material is gradually melted. The screw 43 is retracted as the liquid molding material is fed forward of the screw 43 and accumulated at the front of the cylinder 41 . The number of rotations of the screw 43 is detected using an encoder of the weighing motor 45, for example. The encoder sends a signal to controller 90 indicating the detection result.

During the metering process, the injection motor 46 may be driven to apply a set back pressure to the screw 43 to limit its rapid retraction. The back pressure on the screw 43 is detected using a pressure detector 47, for example. Pressure detector 47 sends a signal indicating the detection result to controller 90 . When the screw 43 is retracted to the set position and a predetermined amount of molding material is accumulated in front of the screw 43, the metering process is completed.

Hereinafter, the injection device 40 will be described again with reference to FIGS. 1 and 2 again.

The injection device 40 has a coupling 51 connected with the screw 43 . Inside the rotor 45a of the metering motor 45, the coupling 51 includes a metering spline shaft 53 splined to the rotor 45a. The metering spline shaft 53 transmits the driving force of the metering motor 45 and the driving force of the injection motor 46 to the screw 43 . The metering spline shaft 53 corresponds to the spline shaft described in claims. An annular groove into which the annular packing 61 is fitted and an annular groove into which the slide ring 62 is fitted are formed on the outer peripheral surface of the coupling 51 .

The annular packing 61 is held by, for example, the coupling 51 , slidably contacts the rotor 45 a of the metering motor 45 , and seals the gap between the rotor 45 a and the coupling 51 . This can prevent the lubricant supplied to the metering spline shaft 53 from leaking to the screw 43 side.

The annular packing 61 may be attached to the metering spline shaft 53 in front of the key 53a of the metering spline shaft 53, and may be attached to the metering spline shaft 53. However, as shown in FIGS. good. The screw attachment portion 52 may have a small diameter portion 52a to which the screw 43 is attached and a large diameter portion 52b larger than the small diameter portion 52a. An annular packing 61 may be arranged in front of the large diameter portion 52b. A rear end portion of the large diameter portion 52 b is connected to the metering spline shaft 53 . Incidentally, as described above, the metering spline shaft 53 may be formed integrally with the screw mounting portion 52 .

As the annular packing 61, for example, an O-ring having a circular cross-sectional shape is used, and is used after being appropriately compressed. The annular packing 61 is made of a softer material than the slide ring 62 in order to ensure sealing performance. Examples of the material of the annular packing 61 include rubber such as butyl rubber.

Although the annular packing 61 is held by the coupling 51 in this embodiment, it is held by the rotor 45a of the metering motor 45 and slidably contacts the coupling 51 so that the rotor 45a and the coupling 51 are held together. gaps may be sealed.

The slide ring 62 is held by the coupling 51 , for example, and slidably contacts the rotor 45 a of the metering motor 45 to align the center line of the rotor 45 a with the center line of the coupling 51 . Thereby, galling between the rotor 45a and the coupling 51 can be suppressed. Moreover, it is possible to suppress the application of an unbalanced load to the annular packing 61 .

The slide ring 62 is made of a material harder than the annular packing 61 in order to suppress eccentricity between the rotor 45a and the coupling 51. As shown in FIG. As a material for the slide ring 62, a crystalline resin or the like having high self-lubricating properties is used. Examples of crystalline resins include polytetrafluoroethylene (PTFE), polyamide (PA), polyesters (PEs), and polyethylene (PE). The greater the degree of crystallinity, the greater the self-lubricating properties. The slide ring 62 may be made of a resin other than a crystalline resin, such as a cloth-filled phenolic resin.

Unlike the annular packing 61, the slide ring 62 does not ensure a sealing performance, so it has a cut partly in the circumferential direction. The cut is formed for attachment and detachment of the slide ring 62 , is widened during attachment and detachment, and is then restored by the elastic restoring force of the slide ring 62 .

Although the slide ring 62 is held by the coupling 51 in this embodiment, it is held by the rotor 45a of the metering motor 45 and is slidably in contact with the coupling 51 so that the center line of the rotor 45a and the cup are aligned. It may be aligned with the center line of the ring 51 . Also, the number of slide rings 62 may be plural.

As shown in FIGS. 1 and 2, a slide ring 62 and an annular packing 61 are arranged in this order from the key 53a side (rear side) of the metering spline shaft 53 toward the screw 43 side (front side). there is The annular packing 61 prevents the lubricant supplied to the metering spline shaft 53 and passed through the slide ring 62 from leaking to the screw 43 side. By supplying the lubricant to the slide ring 62, the sliding resistance of the slide ring 62 can be reduced, and leakage of the lubricant to the screw 43 side can be suppressed. Here, the lubricant supplied to the metering spline shaft 53 passes between the slide ring 62 and the rotor 45 a of the metering motor 45 , between the slide ring 62 and the coupling 51 , and at the gap formed in the slide ring 62 . and so on.

Although the embodiments and the like of the injection molding machine have been described above, the present invention is not limited to the above-described embodiments and the like. Improvements are possible.

40 injection device 41 cylinder 43 screw 45 metering motor 45a rotor 45b stator 46 injection motor 51 coupling 53 metering spline shaft 61 annular packing 62 slide ring 90 control device

Claims (2)

a screw that is rotatably and reciprocally arranged inside a cylinder that heats the molding material ;
a coupling connected to the screw and spline-connected to the inner side of a cylindrical rotor of the metering motor so as to transmit the driving force of the metering motor for rotating the screw and the driving force of the injection motor for advancing and retreating the screw;
an annular packing held by one of the rotor and the coupling and slidably contacting the other;
a slide ring held by one of the rotor and the coupling and slidably contacting the other ;
The injection device , wherein the hardness of the slide ring is harder than the hardness of the annular packing . The slide ring and the annular packing are arranged in this order from the key side of the spline shaft of the coupling toward the screw side,
2. The injection device according to claim 1, wherein said annular packing prevents lubricant supplied to said spline shaft and passed through said slide ring from leaking toward said screw.

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